DKNet

Reserve and complete relational keys

Part of DKNet.AspCore.Idempotency.Relational. The internal IdempotencyRelationalStore<TContext> implements the public core contract. An application selects it through a provider; it cannot derive from the base itself.

using DKNet.AspCore.Idempotency.NpgsqlStore;
using Microsoft.Extensions.DependencyInjection;
var services = new ServiceCollection();
services.AddLogging();
services.AddIdempotencyWithNpgsqlStore("Host=localhost;Database=idempotency;Username=app;Password=local-demo");

The relational store inserts a reservation, reads a unique-index collision, and conditionally reclaims only an expired row.

Each check creates a context from IDbContextFactory<TContext> and attempts to insert a status-102 reservation. A provider-classified unique violation triggers a lookup of the blocking row. A live row returns (true, null) while reserved, or the completed response. An expired row is reclaimed with an ExecuteUpdateAsync whose predicate still requires expiry; exactly one affected row grants the reservation. A losing reclaimer reads the current state and returns a duplicate.

Completion updates status, body, content type and expiry directly. It preserves the reservation’s CreatedAt. If no row remains it attempts an insert; a classified duplicate on that fallback is logged and swallowed. Other database failures propagate to the caller.

The shared store owns an async DI scope for its lifetime and creates a fresh context per operation. It is disposed asynchronously with its scope.

⚙️ Configuration reference

The store reads InFlightReservationTimeout from the core retention settings. It does not read CachePrefix. The filter supplies completed-response expiry.

🧱 Where it fits

The package overview shows the host registrations and dependencies behind this capability. The core filter and selected store have separate responsibilities.

The consumer host selects this package’s components and supplies the runtime dependencies shown in the package architecture.

⚠️ Gotchas & limits

UX_CompositeKey must exist in the database. It is the fresh-reservation concurrency guard.
A handler can outlive its reservation. Completion is keyed by the composite hash and carries no owner token.
A row may be reclaimed after expiry; it is not automatically deleted. There is no cleanup worker.
The shared classes and provider contexts are internal. An external provider implements the core interface instead.

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